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摘要
Physical model experiments on sandbar migration are widely conducted in the wave flume to reveal its hydro-sediment dynamic mechanisms. Selecting an appropriate scale relation is an important part of designing a laboratory experiment. However, evaluating the scale effect is complicated since it is impractical to design wave flume experiments based on strict geometry scales derived from the prototype beach or other laboratory beaches. Here, a process-based numerical model is used to test the Dean and Shields similitudes by comparing sandbar migration and sediment transport in different undistorted model scales using natural sediments. The numerical model provides excellent predictions for both offshore sandbar migration on a real-world beach and onshore sandbar migration in the wave flume. Consistent with previous studies, sandbar offshore migration and suspended sediment transport are similar when the Dean similitude is fulfilled. Sandbar onshore migration and bedload transport can be well reproduced only if the Shields similitude is achieved. Although previous laboratory experiments of sandbar migration generally used the Dean similitude, it is found that the Shields similitude is effective and indispensable for modelling sandbar onshore migration, which will be underestimated if the Dean similitude is only considered. Each scale relation cannot be used simultaneously for modelling both onshore and offshore sandbar migration in physical models.
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单位河海大学
